A fuel filter system for conditioning the fuel of an internal combustion engine, such as a diesel engine, should separate air and water from fuel at a point between the fuel supply tank and the engine. Air is less dense than the fuel, and water is more dense than the fuel. Thus, air must be removed from an upper portion of the fuel filter system, and water must be removed from a lower portion of the fuel filter system. These requirements have resulted in special fittings being provided on the filter cartridge of a fuel filter system, including a fitting adjacent to an upper portion of the fuel filter cartridge for bleeding air, and/or a fitting near a lower portion of the filter cartridge for draining water which collects in a lower sump portion of the filter cartridge. A fitting adds manufacturing cost to the fuel filter cartridge; a fitting requires hose material to be routed to the fuel filter cartridge; and, a fitting increases the service time required to change a fuel filter cartridge.
Thus, it would be desirable, and it is an object of the present invention, to provide a fuel filter system having a fuel filter head and a fuel filter cartridge, which continuously removes water and particulates from liquid fuel and returns the contaminated liquid to a fuel tank, during operation of an associated internal combustion engine, without requiring an external fitting on the fuel filter cartridge.
It is another object of the invention to provide a fuel filter system having a fuel filter head and a fuel filter cartridge, which continuously removes air from liquid fuel, during operation of an associated internal combustion engine, without requiring an external fitting on the fuel filter cartridge.